I was thinking about this the other night.  Obviously there was only a certain number of each pin made.  Back in those days, I'm guessing the vast majority of pins were purchased by operators / distributors for commercial businesses.  Most of that has dried up now.
From the Tilt DVD, it was mentioned that Europe was one of their biggest customers (50-70%).  So with an Addams Family,  roughly maybe 10,000 of those in Europe.  From Matts threads on AP and AA - it would seem that roughly maybe 30 or so people own this machine.  I guess there is a good percentage of owners not on either site, so I'll round it up to 100.

I think now that there is a known market for pins now will hopefully stop them being sent to the tip.

Eventually it will dry up, thus driving their value up.  I don't think I would see it in my lifetime of collecting.  I guess for the Commercial guys who are hunting these down can answer this better..!